To understand this page, you need to read from left to right. That’s how the Greeks set up their alphabet, one of the precursors to our own. But in written Arabic, words flow in the opposite direction, and in Chinese, characters run top to bottom. Researchers have found that the direction of your writing determines how you orient the arrow of time. When asked to organize events in a line from earliest to latest, English readers arranged them left to right, Arabic right to left, and Chinese top to bottom. People without writing systems, like Papua New Guinea’s Yupno, had a free-form approach.